Administering a Cluster

Creating the kubectl config

kubectl is the command line client used to control a kubernetes cluster. Kubernetes uses a separate authentication mechanism from OpenStack (Keystone). Since OpenStack already knows who we are, we can use it to generate a kubectl config file that includes credentials to authenticate us to Kubernetes.

1. Create a new directory and cd to it;

   mkdir mycluster
   cd mycluster
   

2. Use the openstack tool to generate the config file for kubectl:

   $ openstack coe cluster config mycluster
   export KUBECONFIG=/home/jake/temp/coe/mycluster/config
   

3. Set the KUBECONFIG environment variable used by copy-and-pasting the export KUBECONFIG=... line output by the above to the shell prompt:

   $ export KUBECONFIG=/home/jake/temp/coe/mycluster/config
   $ echo $KUBECONFIG
   /home/jake/temp/coe/mycluster/config
   

Using kubectl

1. Use kubectl to see if all your service pods in kubernetes are set up correctly. All the pods in the kube-system namespace should have status Running. For example:

   $ kubectl get all --all-namespaces
   NAMESPACE                NAME                                                                 READY   STATUS      RESTARTS       AGE
   calico-apiserver         pod/calico-apiserver-79dbf75bfc-997sh                                1/1     Running     0              45d
   calico-apiserver         pod/calico-apiserver-79dbf75bfc-wjqsz                                1/1     Running     0              45d
   calico-system            pod/calico-kube-controllers-5c7ffcfbf9-q75rz                         1/1     Running     0              45d
   calico-system            pod/calico-node-49dsv                                                1/1     Running     2 (45d ago)    45d
   calico-system            pod/calico-node-q69tj                                                1/1     Running     0              45d
   calico-system            pod/calico-typha-6c874f96b5-7w7pv                                    1/1     Running     0              45d
   calico-system            pod/csi-node-driver-hl9jm                                            2/2     Running     0              45d
   calico-system            pod/csi-node-driver-jqwrv                                            2/2     Running     0              45d
   kube-system              pod/coredns-7c65d6cfc9-fzqmp                                         1/1     Running     0              45d
   kube-system              pod/coredns-7c65d6cfc9-n7l9p                                         1/1     Running     0              45d
   [output truncated]
   

Using the web interface

Magnum also sets up the Kubernetes Web UI by default. Follow these steps to access it.

1. Create a clusterrolebinding for the kubernetes-dashboard service account

   kubectl create clusterrolebinding kubernetes-dashboard --clusterrole=cluster-admin --serviceaccount=kubernetes-dashboard:kubernetes-dashboard
   

2. Get the dashboard token. Run the following code, and copy the resulting output to your clipboard

   kubectl create token kubernetes-dashboard -n kubernetes-dashboard
   

3. Use kubectl to create a web proxy

   $ kubectl proxy
   Starting to serve on 127.0.0.1:8001
   

4. Using a browser, visit the dashboard URL. The URL is http://localhost:8001/api/v1/namespaces/kubernetes-dashboard/services/https:kubernetes-dashboard:443/proxy/

5. Select the token option, and paste the token you copied into the field provided. Click login and you should be taken to an overview of your cluster.